Ferrite core for deflecting yoke, surface polishing apparatus and grindstone therefor

Abstract

A surface polishing apparatus for polishing a surface of a ferrite core for a deflecting yoke is disclosed. The surface polishing apparatus is used to polish an inner wall surface of a hole portion and an outer wall surface of a lower end portion of a substantially trumpet-shaped ferrite core having a diameter increasing from an upper end portion thereof to the lower end portion thereof. In the surface polishing apparatus, the inner wall surface of the hole portion and the outer wall surface the lower end portion of the ferrite core are polished simultaneously using a grindstone whose grinding surfaces to be respectively contacted with the inner wall surface of the hole portion and the outer wall surface of the lower end portion of the ferrite core are formed integral with each other.

What is claimed is:  
     
         1 . A surface polishing apparatus for polishing a substantially trumpet-shaped ferrite core for a deflecting yoke, the ferrite core including a hole portion and a connecting portion having a diameter increasing from an upper end portion thereof to a lower end portion thereof, said surface polishing apparatus comprising: 
 a grindstone including grinding surfaces to be respectively contacted with an inner wall surface of the hole portion of the ferrite core and an outer wall surface of the lower end portion of the ferrite core,    wherein said grinding surfaces are formed integral with each other and simultaneously polish at least the inner wall surface of the hole portion and the outer wall surface of the lower end portion of the ferrite core.    
     
     
         2 . The surface polishing apparatus according to  claim 1 , further comprising: 
 a securing member for securing the upper end portion of the ferrite core;    a holding member for holding said grindstone; and    a driving member for contacting said grindstone with the ferrite core and for driving and rotating at least one of said securing member and said holding member.    
     
     
         3 . The surface polishing apparatus according to  claim 1 , wherein said grindstone simultaneously polishes a bottom wall surface of the ferrite core.  
     
     
         4 . A grindstone for polishing a substantially trumpet-shaped ferrite core for a deflecting yoke, the ferrite core including a hole portion and a connecting portion having a diameter increasing from an upper end portion thereof to a lower end portion thereof, said grindstone comprising: 
 a first grinding portion for contacting with an inner wall surface of the hole portion of the ferrite core and having a shape similar to the hole portion of the ferrite core; and    a second grinding portion for contacting with at least one of a bottom wall surface and an outer wall surface of the lower end portion of the ferrite core,    wherein said first grinding portion and said second grinding portion are integrally formed.    
     
     
         5 . The grindstone according to  claim 4 , 
 wherein said first grinding portion includes a pillar-shaped projecting portion having a diameter increasing from an upper end portion thereof to a lower end portion thereof, and    wherein said second grinding portion includes: 
 a disk-shaped seat surface portion connected to said pillar-shaped projecting portion; and  
 an outer periphery projecting portion provided along said disk-shaped seat surface portion and projected therefrom in a periphery of said pillar-shaped projecting portion.  
   
     
     
         6 . The grindstone according to  claim 5 , wherein said outer periphery projecting portion includes a plurality of grooves provided between an inner wall surface and an outer wall surface thereof.  
     
     
         7 . The grindstone according to  claim 5 , wherein said pillar-shaped projecting portion includes a plurality of spiral-shaped groove portions on a side surface thereof.  
     
     
         8 . The grindstone according to  claim 6 , wherein said pillar-shaped projecting portion includes a plurality of spiral-shaped groove portions on a side surface thereof.  
     
     
         9 . A substantially trumpet-shaped ferrite core for a deflecting yoke, comprising: 
 a hole portion; and    a connecting portion having a diameter increasing from an upper end portion thereof to a lower end portion thereof,    wherein at least an inner wall surface of said hole portion and an outer wall surface of said lower end portion are polished simultaneously by a grindstone whose grinding surfaces to be respectively contacted with said inner wall surface of said hole portion and said outer wall surface of said lower end portion are formed integral with each other.    
     
     
         10 . The ferrite core according to  claim 9 , wherein said inner wall surface of said hole portion and said outer wall surface of said lower end portion have a coaxiality deviation of 0.03 mm or less.